Merge branch '6.4' into 7.0

* 6.4:
  [AssetMapper] Allow simple, relative paths in importmap.php
  [PropertyInfo] Make isWriteable() more consistent with isReadable() when checking snake_case properties
  [AssetMapper] Add support for CSS files in the importmap
  [Messenger] Add `--all` option to the `messenger:failed:remove` command
  Fix merge
  fix #51235 - fix the order of merging of serializationContext and self::CONTEXT_DENORMALIZE
  [HttpClient] Fix Static Code Analyzer issue with JsonMockResponse
  [Messenger] Fix exiting `FailedMessagesRetryCommand`
  [Serializer] Fix reindex normalizedData array in AbstractObjectNormalizer::denormalize()
  remove an unreachable code branch
  [Validator] Fix `File::$extensions`’ PHPDoc
  [Mime] Fix email (de)serialization issues
  [FrameworkBundle][WebProfilerBundle][Console][Form][HttpKernel][PropertyInfo][Validator] Remove optional before required param
  Replace usages of SkippedTestSuiteError with markTestSkipped() call
  Update InteractiveAuthenticatorInterface description wording to match documentation
  [Serializer] Fix parsing XML root node attributes
  fix parsing of payload timestamp to DateTimeImmutable
  Fix routing to multiple fallback transports
  Fix missing stamps in delayed message handling
  [DoctrineBridge] Ignore invalid stores in `LockStoreSchemaListener` raised by `StoreFactory`

Author: nicolas-grekas

Part/DataPart.php

@@ -154,7 +154,7 @@ public function __wakeup(): void
             throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
         }
         foreach (['body', 'charset', 'subtype', 'disposition', 'name', 'encoding'] as $name) {
-            if (null !== $this->_parent[$name] && !\is_string($this->_parent[$name])) {
+            if (null !== $this->_parent[$name] && !\is_string($this->_parent[$name]) && !$this->_parent[$name] instanceof File) {
                 throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
             }
             $r = new \ReflectionProperty(TextPart::class, $name);

Part/TextPart.php

@@ -222,7 +222,7 @@ private function chooseEncoding(): string
     public function __sleep(): array
     {
         // convert resources to strings for serialization
-        if (null !== $this->seekable || $this->body instanceof File) {
+        if (null !== $this->seekable) {
             $this->body = $this->getBody();
             $this->seekable = null;
         }

Tests/EmailTest.php

@@ -658,4 +658,34 @@ public function testBodyCache()
         $body2 = $email->getBody();
         $this->assertNotSame($body1, $body2, 'The two bodies must not reference the same object, so the body cache does not ensure that the hash for the DKIM signature is unique.');
     }
+
+    public function testAttachmentBodyIsPartOfTheSerializationEmailPayloadWhenUsingAttachMethod()
+    {
+        $email = new Email();
+        $email->attach(file_get_contents(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt') ?: '');
+
+        $this->assertTrue(str_contains(serialize($email), 'foo_bar_xyz_123'));
+    }
+
+    public function testAttachmentBodyIsNotPartOfTheSerializationEmailPayloadWhenUsingAttachFromPathMethod()
+    {
+        $email = new Email();
+        $email->attachFromPath(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt');
+
+        $this->assertFalse(str_contains(serialize($email), 'foo_bar_xyz_123'));
+    }
+
+    public function testEmailsWithAttachmentsWhichAreAFileInstanceCanBeUnserialized()
+    {
+        $email = new Email();
+        $email->attachFromPath(__DIR__.\DIRECTORY_SEPARATOR.'Fixtures'.\DIRECTORY_SEPARATOR.'foo_attachment.txt');
+
+        $email = unserialize(serialize($email));
+        $this->assertInstanceOf(Email::class, $email);
+
+        $attachments = $email->getAttachments();
+
+        $this->assertCount(1, $attachments);
+        $this->assertStringContainsString('foo_bar_xyz_123', $attachments[0]->getBody());
+    }
 }

Tests/Fixtures/foo_attachment.txt

@@ -0,0 +1 @@
+foo_bar_xyz_123